The present invention relates generally to optical fiber connectors and, more particularly, to an assembly and method for furcating optical fibers that constitutes an alternative embodiment of the invention disclosed in the previously-referenced parent application.
In recent years, electro-optical equipment has begun to replace electronic equipment for certain applications, such as telecommunication and data communication networks. This trend should continue because the electro-optical equipment has inherent advantages over purely electronic equipment. These advantages include a broader bandwidth for signal transmission, greater storage capability for data, and inherent immunity to electromagnetic interference. Given these advantages of electro-optical equipment, fiber optic cables have become increasingly important because they transmit information and signals between the various pieces of electro-optical equipment.
The appearance of these cables resemble electrical cables, but fiber optic cables are smaller in size and lighter in weight. Fiber optic cables comprise optical fibers and other cable elements which are protected from the external environment by an external jacketing. These cables may be of a traditional design with the fibers surrounded by strength members and protective elements in the cable core or of a more non-traditional, loosely-bundled type with the fibers contained loosely within tubes or ducts in a cable core.
Whether traditional or loosely-bundled, all types of optical fiber cables may contain groups of optical fibers with no individual protective jacketing or strength members. These fibers are typically 250 micrometers or 500 micrometers in diameter. At the ends of the fiber optic cables, the small unprotected fibers must be removed from the outer protective cable structure and inserted into fiber optic connection devices (connectors or splices). Due to the small size of the fibers and the lack of protective coverings over the individual fibers, connectorization and splicing is difficult. Special protective equipment must be used to organize the loose fibers and to protect the completed connections. In order to make the installation of fiber cables reliable and efficient, there exists a need in the art for a furcation unit which allows individual optical fibers to be easily handled, connectorized, and spliced. Further, in order to prevent degradation of the prepared fibers, the furcation unit must protect the fiber ends from moisture, dust, and other contaminants.
The fiber optic furcation unit disclosed in the previously-referenced parent application Ser. No. 08/944,105 fulfills this need in the art, thereby allowing for fast, efficient installation by field technicians. The present invention constitutes an alternative embodiment of the invention disclosed in the above-referenced parent application.
The present invention encompasses an assembly that includes a fiber-containing structure that contains a plurality of optical fibers and a furcation tube assembly that includes a plurality of loose tube optical fiber cables. Each of the loose tube optical fiber cables includes a hollow inner tube; a support structure that includes strength members, the support structure surrounding the hollow inner tube; and, a protective jacket surrounding the support structure. The assembly further includes a heat shrink tube that joins the fiber-containing structure and the furcation tube assembly and a protective tube surrounded by the heat shrink tube and disposed in surrounding relationship to the furcation tube assembly. The support structure extends in a first direction between an outer surface of the fiber-containing structure and an inner surface of the protective tube proximate a first end of the protective tube. In one embodiment, the support structure is folded back and further extends in a second direction opposite to the first direction between an outer surface of the protective tube and an inner surface of the heat shrink tube. In another embodiment, the support structure extends in the second direction to a prescribed termination point that is located intermediate opposite ends of the protective tube. In another embodiment, the support structure extends in the second direction to a prescribed termination point that is located proximate a second end of the protective tube that is opposite the first end of the protective tube. In yet another embodiment, the support structure extends in the second direction to a prescribed termination point that is located beyond a second end of the protective tube that is opposite the first end of the protective tube. The protective tube is preferably made of a rigid material that provides structural support to withstand bending and tensile loads, and the heat shrink tube is preferably an adhesive-coated heat shrink tube.
In another of its aspects, the present invention encompasses a method that includes the steps of providing a fiber-containing structure that contains a plurality of optical fibers; providing a furcation tube assembly that includes a plurality of loose tube optical fiber cables; joining the fiber-containing structure and the furcation tube assembly with a heat shrink tube; coupling the plurality of optical fibers to respective ones of the plurality of loose tube optical fiber cables; and, assembling a protective tube in surrounding relationship to the furcation tube assembly and inside of the heat shrink tube in substantially concentric relationship thereto. The step of providing a furcation tube assembly that includes a plurality of loose tube optical fiber cables includes the sub-steps of providing a plurality of hollow inner tubes; constructing a support structure in surrounding relationship to the plurality of hollow inner tubes; extending the support structure in a first direction between an outer surface of the fiber-containing structure and an inner surface of the protective tube proximate a first end of the protective tube; and, assembling a protective jacket in surrounding relationship to the support structure. The method preferably further includes the step of connectorizing the plurality of loose tube optical fiber cables to a fiber optic splice or a fiber optic connector.